Road to Moscow is the Name of the Game,there is no Dunkirk.

I have played a new Campain and Leningrad is a must take,there are no other Waypoints to choose ,if you came at this Point.Can you give me a cheatcode ,that i can Leningradmission acomplished and can go one.

Is Leningrad a Gamepoint that can not left over?Can i take a other way direct to Moskow?Historic correct is that not, that the troops that were at Leningrad ,then go to Moskow.